The present invention is directed to printed circuit boards and more particularly to an apparatus for testing printed circuit boards.
As the complexity of printed circuit boards increases, the equipment for testing the circuit boards becomes more complex. The usual arrangement for testing printed circuit boards is to position a probe board on top of the circuit board to be tested, in which probe board there is included a plurality of spring-biased probe members positioned to engage corresponding electrical locations in the printed circuit board. Movement of the probe board towards the circuit board provides the required contact between the probe members and the electrical locations. Each of the probe members carried by the probe board is wired to an interface member whereby a circuit is established between a control system located outside of the test equipment and electrical location on the circuit board upon contact between the probe members and the electrical locations. With the number of electrical locations on the circuit boards increasing, together with the corresponding increase of circuit boards having different configurations of electrical locations, the alignment of the probe members with the electrical locations becomes quite critical and requires costly complex test fixtures to accomplish such alignment.
To reduce such cost and simplify the structure of the test fixtures, test fixtures have been developed using a converter board which electrically connects probe members arranged in a uniform rectangular grid on a board member positioned adjacent the top surface of the converter board with randomly arranged contact points of a printed circuit board positioned against the lower surface of the converter board. An example of this arrangement is found in U.S. Pat. No. 3,654,585. However, it has been found that for large printed circuit boards or circuit boards having wired elements such as chokes, capacitors, etc. located on the surface, the above constructed converter board arrangement will not work. It is therefore a principal object of this invention to provide a test fixture overcoming the above-cited problems of the prior art.
It is another object of the present invention to provide a test fixture for testing a large number of different circuit board configurations which is low in cost.